An association between YKL-40 and type 2 diabetes in psychotic disorders

OBJECTIVE

This study examines if YKL-40 is increased in individuals with psychotic disorders and if elevated YKL-40 levels at baseline is associated with subsequent development of type 2 diabetes.

METHOD

A total of 1383 patients with a diagnosis of schizophrenia or affective psychosis and 799 healthy controls were recruited in the period 2002-2015. Plasma YKL-40 and metabolic risk factors were measured and medication was recorded. Using national registry data, association between baseline risk factors and later development of type 2 diabetes was assessed using Cox proportional hazards models.

RESULTS

Plasma YKL-40 was higher in patients vs. healthy controls also after adjusting for metabolic risk factors, with no difference between the schizophrenia and affective psychosis groups. Patients were diagnosed with type 2 diabetes at a significantly younger age. Multivariate Cox regression analyses showed that elevated YKL-40 (hazard ratio (HR) = 5.6, P = 0.001), elevated glucose (HR = 3.6, P = 0.001), and schizophrenia diagnosis (HR = 3.0, P = 0.014) at baseline were associated with subsequent development of type 2 diabetes.

CONCLUSIONS

Patients with psychotic disorders have at baseline increased levels of YKL-40 beyond the effect of comorbid type 2 diabetes and metabolic risk factors. Elevated YKL-40 level at baseline is associated with later development of type 2 diabetes.

Maternal Perinatal and Concurrent Anxiety and Mental Health Problems in Early Childhood: A Sibling-Comparison Study

Do associations between maternal anxiety symptoms and offspring mental health remain after comparing differentially exposed siblings? Participants were 17,724 offspring siblings and 11,553 mothers from the Norwegian Mother and Child Cohort study. Mothers reported anxiety and depressive symptoms at 30 weeks' gestation, and 0.5, 1.5, 3, and 5 years postpartum. Child internalizing and externalizing problems were assessed at ages 1.5, 3, and 5, and modeled using multilevel analyses with repeated measures nested within siblings, nested within mothers. Maternal pre- and postnatal anxiety were no longer associated with child internalizing or externalizing problems after adjusting for maternal depression and familial confounding. Maternal anxiety when the children were in preschool age, however, remained significantly associated with child internalizing but not externalizing problems.

Genetically Informative Mediation Modeling Applied to Stressors and Personality-Disorder Traits in Etiology of Alcohol Use Disorder

A statistical mediation model was developed within a twin design to investigate the etiology of alcohol use disorder (AUD). Unlike conventional statistical mediation models, this biometric mediation model can detect unobserved confounding. Using a sample of 1410 pairs of Norwegian twins, we investigated specific hypotheses that DSM-IV personality-disorder (PD) traits mediate effects of childhood stressful life events (SLEs) on AUD, and that adulthood SLEs mediate effects of PDs on AUD. Models including borderline PD traits indicated unobserved confounding in phenotypic path coefficients, whereas models including antisocial and impulsive traits did not. More than half of the observed effects of childhood SLEs on adulthood AUD were mediated by adulthood antisocial and impulsive traits. Effects of PD traits on AUD 5‒10 years later were direct rather than mediated by adulthood SLEs. The results and the general approach contribute to triangulation of developmental origins for complex behavioral disorders.

Diagnosis of hyperkinetic disorder among children in Norway

BACKGROUND

Hyperkinetic disorder is one of the most frequently used psychiatric diagnoses among children and adolescents in Norway. It has previously been shown that use of the diagnosis varies widely by county.

MATERIAL AND METHOD

We estimated the proportion of children with hyperkinetic disorder using patient data from the Norwegian Patient Registry and population data from the Norwegian Population Registry. The estimations were made for both Norway as a whole and by county. Assessment and documentation of the diagnosis were surveyed by linking the Norwegian Patient Registry and the Norwegian Mother and Child Cohort Study. We reviewed medical records from specialist mental health services for children and adolescents and assessed whether the diagnoses met the research criteria for hyperkinetic disorder.

RESULTS

At 12 years of age, 5.4 % of Norwegian boys and 2.1 % of Norwegian girls had been diagnosed with hyperkinetic disorder by specialist health services. The proportion of children varied between 1.4 % and 5.5 % among the counties. A review of medical records for 549 children showed that 49 % of the diagnoses were reliably documented in the records. The main reasons that the diagnosis was not documented were a discrepancy between the information in the medical record and diagnostic criteria (38 %) and inadequate differential diagnostic assessment (46 %).

INTERPRETATION

There was considerable geographic variation in the proportions of children and adolescents with hyperkinetic disorder. A large percentage of the diagnoses were not reliably documented in medical records. The guideline for evaluation, diagnostics and medical recordkeeping should be reviewed.

Maternal prenatal depressive symptoms and risk for early-life psychopathology in offspring: genetic analyses in the Norwegian Mother and Child Birth Cohort Study

BACKGROUND

Maternal prenatal depression is a known risk factor for early-life psychopathology among offspring; however, potential risk transmission mechanisms need to be distinguished. We aimed to test the relative importance of passive genetic transmission, direct exposure, and indirect exposure in the association between maternal prenatal depressive symptoms and early-life internalising and externalising psychopathology in offspring.

METHODS

We used structural equation modelling of phenotypic data and genetically informative relationships from the families of participants in the Norwegian Mother and Child Birth Cohort Study (MoBa). The analytic subsample of MoBa used in the current study comprises 22 195 mothers and 35 299 children. We used mothers' self-reported depressive symptoms during pregnancy, as captured by the Symptom Checklist, and their reports of symptoms of psychopathology in their offspring during the first few years of life (measured at 18, 36, and 60 months using the Child Behavior Checklist).

FINDINGS

Maternal prenatal depressive symptoms were found to be associated with early-life psychopathology primarily via intergenerationally shared genetic factors, which explained 41% (95% CI 36-46) of variance in children's internalising problems and 37% (30-44) of variance in children's externalising problems. For internalising problems, phenotypic transmission also contributed significantly, accounting for 14% (95% CI 5-19) of the association, but this contribution was found to be explained by exposure to concurrent maternal depressive symptoms, rather than by direct exposure in utero.

INTERPRETATION

Associations between maternal prenatal depressive symptoms and offspring behavioural outcomes in early childhood are likely to be at least partially explained by shared genes. This genetic confounding should be considered when attempting to quantify risks posed by in-utero exposure to maternal depressive symptoms.

FUNDING

UK Economic and Social Research Council, Norwegian Research Council, Norwegian Ministries of Health and Care Services, and Education & Research, Wellcome Trust, Royal Society, and National Institute for Health Research.

Associations between personality disorders and cannabis use and cannabis use disorder: a population-based twin study

BACKGROUND AND AIMS

Individual differences in DSM-IV personality disorders (PDs) are associated with increased prevalence of substance use disorders. Our aims were to determine which combination of PDs trait scores best predict cannabis use (CU) and cannabis use disorder (CUD), and to estimate the size and significance of genetic and environmental risks in PD traits shared with CU and CUD.

DESIGN

Linear mixed-effects models were used to identify PD traits for inclusion in twin analyses to explore the genetic and environmental associations between the traits and cannabis use.

SETTING

Cross-sectional data were obtained from Norwegian adult twins in a face-to-face interview in 1999-2004 as part of a population-based study of mental health.

PARTICIPANTS

Subjects were 1419 twins (μage  = 28.2 years, range = 19-36) from the Norwegian Institute of Public Health Twin Panel with complete PD and cannabis data.

MEASUREMENTS

PD traits were assessed using DSM-IV criteria. Life-time CU and CUD were based on DSM-IV abuse and dependence criteria, including withdrawal and craving.

FINDINGS

After adjusting for age and sex, antisocial [β = 0.23, 95% confidence interval (CI) = 0.19-0.28] and borderline PDs (β = 0.20, 95% CI = 0.14-0.26) were associated strongly with CU. Antisocial (β = 0.26, 95% CI = 0.21-0.31) and borderline PDs (β = 0.12, 95% CI = 0.06-0.18) were also linked strongly to CUD. Genetic risks in antisocial and borderline PD traits explained 32-60% of the total variance in CU and CUD. Dependent and avoidant PDs explained 11 and 16% of the total variance in CU and CUD, respectively.

CONCLUSIONS

Individual differences in the liability to cannabis use and cannabis use disorder appear to be linked to genetic risks correlated with antisocial and borderline personality disorder traits.

Association of Gestational Age at Birth With Symptoms of Attention-Deficit/Hyperactivity Disorder in Children

Importance

Preterm birth is associated with an increased risk of attention-deficit/hyperactivity disorder (ADHD); however, it is unclear to what extent this association can be explained by shared genetic and environmental risk factors and whether gestational age at birth is similarly related to inattention and hyperactivity/impulsivity and to the same extent in boys and girls.

Objectives

To investigate the association between gestational age at birth and symptoms of ADHD in preschool and school-age children after adjusting for unmeasured genetic and environmental risk factors.

Design, Setting, and Participants

In this prospective, population-based cohort study, pregnant women were recruited from across Norway from January 1, 1999, through December 31, 2008. Results of a conventional cohort design were compared with results from a sibling-comparison design (adjusting for genetic and environmental factors shared within families) using data from the Norwegian Mother and Child Cohort Study. Data analysis was performed from October 1, 2017, through March 16, 2018.

Exposures

Analyses compared children and siblings discordant for gestational age group: early preterm (delivery at gestational weeks 22-33), late preterm (delivery at gestational weeks 34-36), early term (delivery at gestational weeks 37-38), delivery at gestational week 39, reference group (delivery at gestational week 40), delivery at gestational week 41, and late term (delivery after gestational week 41).

Main Outcomes and Measures

Maternally reported symptoms of ADHD in children at 5 years of age and symptoms of inattention and hyperactivity/impulsivity at 8 years of age. Covariates included child and pregnancy characteristics associated with the week of delivery and the outcomes.

Results

A total of 113 227 children (55 187 [48.7%] female; 31 708 [28.0%] born at gestational week 40), including 33 081 siblings (16 014 female [48.4%]; 9705 [29.3%] born at gestational week 40), were included in the study. Children born early preterm were rated with more symptoms of ADHD, inattention, and hyperactivity/impulsivity than term-born children. After adjusting for unmeasured genetic and environmental factors, children born early preterm had a mean score that was 0.24 SD (95% CI, 0.14-0.34) higher on ADHD symptom tests, 0.33 SD (95% CI, 0.24-0.42) higher on inattention tests, and 0.23 SD (95% CI, 0.14-0.32) higher on hyperactivity/impulsivity tests compared with children born at gestational week 40. Sex moderated the association of gestational age with preschool ADHD symptoms, and the association appeared to be strongest among girls. Early preterm girls scored a mean of 0.8 SD (95% CI, 0.12-1.46; P = .02) higher compared with their term-born sisters.

Conclusions and Relevance

After accounting for unmeasured genetic and environmental factors, early preterm birth was associated with a higher level of ADHD symptoms in preschool children. Early premature birth was associated with inattentive but not hyperactive symptoms in 8-year-old children. This study demonstrates the importance of differentiating between inattention and hyperactivity/impulsivity and stratifying on sex in the study of childhood ADHD.

Maternal alcohol use during pregnancy and offspring attention-deficit hyperactivity disorder (ADHD): a prospective sibling control study

Background

Maternal alcohol use during pregnancy has repeatedly been associated with development of attention-deficit hyperactivity disorder (ADHD) in the offspring. It is, however not known whether this reflects a direct casual intra-uterine effect or a non-causal relationship due to confounding. We used three different approaches to control for measured and unmeasured confounding: statistical adjustment for covariates, negative control comparison against maternal pre-pregnancy alcohol use, and comparison among differentially exposed siblings.

Methods

The sample comprised 114 247 children (34 283 siblings) from 94 907 mothers, recruited to the Norwegian Mother and Child Birth Cohort Study between 1999 and 2008. Self-reported measurements of alcohol use were obtained in week 30 during the pregnancy. Mothers rated offspring ADHD symptoms at 5 years on two measures. Clinical ADHD diagnoses were obtained from the Norwegian Patient Registry.

Results

We found an overall positive association between maternal alcohol use during pregnancy and offspring ADHD symptoms, which was only marginally attenuated after inclusion of measured covariates. Both the negative control and the sibling comparison analysis further attenuated the estimated association, but it remained greater than zero [β = 0.017, 95% confidence interval (CI) = 0.005-0.030). No association was found between maternal alcohol use during pregnancy and offspring ADHD diagnosis.

Conclusions

For offspring ADHD symptoms we found a weak, but possibly causal association with maternal alcohol use during pregnancy, but no such effect was observed for clinical ADHD diagnosis.

A Twin Study of Normative Personality and DSM-IV Personality Disorder Criterion Counts: Evidence for Separate Genetic Influences

OBJECTIVE

Both normative personality and DSM-IV personality disorders have been found to be heritable. However, there is limited knowledge about the extent to which the genetic and environmental influences underlying DSM personality disorders are shared with those of normative personality. The aims of this study were to assess the phenotypic similarity between normative and pathological personality and to investigate the extent to which genetic and environmental influences underlying individual differences in normative personality account for symptom variance across DSM-IV personality disorders.

METHOD

A large population-based sample of adult twins was assessed for DSM-IV personality disorder criteria with structured interviews at two waves spanning a 10-year interval. At the second assessment, participants also completed the Big Five Inventory, a self-report instrument assessing the five-factor normative personality model. The proportion of genetic and environmental liabilities unique to the individual personality disorder measures, and hence not shared with the five Big Five Inventory domains, were estimated by means of multivariate Cholesky twin decompositions.

RESULTS

The median percentage of genetic liability to the 10 DSM-IV personality disorders assessed at wave 1 that was not shared with the Big Five domains was 64%, whereas for the six personality disorders that were assessed concurrently at wave 2, the median was 39%. Conversely, the median proportions of unique environmental liability in the personality disorders for wave 1 and wave 2 were 97% and 96%, respectively.

CONCLUSIONS

The results indicate that a moderate-to-sizable proportion of the genetic influence underlying DSM-IV personality disorders is not shared with the domain constructs of the Big Five model of normative personality. Caution should be exercised in assuming that normative personality measures can serve as proxies for DSM personality disorders when investigating the etiology of these disorders.

Analysis of shared heritability in common disorders of the brain

Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.

Emotional Lability in Preschoolers With Symptoms of ADHD

OBJECTIVE

The aim of this study was to examine occurrence of emotional lability (EL) in preschoolers with ADHD symptoms versus controls.

METHOD

The study was part of the Norwegian Mother and Child Cohort Study (MoBa) at the Norwegian Institute of Public Health. In the present study, 495 preschoolers were clinically examined. Symptoms of ADHD, anxiety, and oppositional defiant disorder (ODD) were measured with the Preschool Age Psychiatric Assessment Interview. An EL measure was obtained from the Emotional Control subscale of the Behavior Rating Inventory of Executive Function-Preschool Version (BRIEF-P), which parents and teachers completed.

RESULTS

EL was significantly more frequent in the ADHD group compared with controls (25% vs. 7%, p < .001). By parent report, EL correlated significantly with ADHD-, anxiety-, and ODD symptoms. By teacher report, EL was significantly correlated only with hyperactivity-impulsivity.

CONCLUSION

EL appears identifiable in young preschoolers and was particularly associated with ODD in children with ADHD symptoms.

Prenatal Phthalates, Maternal Thyroid Function, and Risk of Attention-Deficit Hyperactivity Disorder in the Norwegian Mother and Child Cohort

BACKGROUND

There is growing concern that phthalate exposures may have an impact on child neurodevelopment. Prenatal exposure to phthalates has been linked with externalizing behaviors and executive functioning defects suggestive of an attention-deficit hyperactivity disorder (ADHD) phenotype.

OBJECTIVES

We undertook an investigation into whether prenatal exposure to phthalates was associated with clinically confirmed ADHD in a population-based nested case-control study of the Norwegian Mother and Child Cohort (MoBa) between the years 2003 and 2008.

METHODS

Phthalate metabolites were measured in maternal urine collected at midpregnancy. Cases of ADHD (n=297) were obtained through linkage between MoBa and the Norwegian National Patient Registry. A random sample of controls (n=553) from the MoBa population was obtained.

RESULTS

In multivariable adjusted coexposure models, the sum of di-2-ethylhexyl phthalate metabolites (∑DEHP) was associated with a monotonically increasing risk of ADHD. Children of mothers in the highest quintile of ∑DEHP had almost three times the odds of an ADHD diagnosis as those in the lowest [OR=2.99 (95% CI: 1.47, 5.49)]. When ∑DEHP was modeled as a log-linear (natural log) term, for each log-unit increase in exposure, the odds of ADHD increased by 47% [OR=1.47 (95% CI: 1.09, 1.94)]. We detected no significant modification by sex or mediation by prenatal maternal thyroid function or by preterm delivery.

CONCLUSIONS

In this population-based case-control study of clinical ADHD, maternal urinary concentrations of DEHP were monotonically associated with increased risk of ADHD. Additional research is needed to evaluate potential mechanisms linking phthalates to ADHD. https://doi.org/10.1289/EHP2358.

Investigation of common, low-frequency and rare genome-wide variation in anorexia nervosa

Anorexia nervosa (AN) is a complex neuropsychiatric disorder presenting with dangerously low body weight, and a deep and persistent fear of gaining weight. To date, only one genome-wide significant locus associated with AN has been identified. We performed an exome-chip based genome-wide association studies (GWAS) in 2158 cases from nine populations of European origin and 15 485 ancestrally matched controls. Unlike previous studies, this GWAS also probed association in low-frequency and rare variants. Sixteen independent variants were taken forward for in silico and de novo replication (11 common and 5 rare). No findings reached genome-wide significance. Two notable common variants were identified: rs10791286, an intronic variant in OPCML (P=9.89 × 10-6), and rs7700147, an intergenic variant (P=2.93 × 10-5). No low-frequency variant associations were identified at genome-wide significance, although the study was well-powered to detect low-frequency variants with large effect sizes, suggesting that there may be no AN loci in this genomic search space with large effect sizes.

Novel Loci Associated With Attention-Deficit/Hyperactivity Disorder Are Revealed by Leveraging Polygenic Overlap With Educational Attainment

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is a common and highly heritable psychiatric condition. By exploiting the reported relationship between ADHD and educational attainment (EA), we aimed to improve discovery of ADHD-associated genetic variants and to investigate genetic overlap between these phenotypes.

METHOD

A conditional/conjunctional false discovery rate (condFDR/conjFDR) method was applied to genome-wide association study (GWAS) data on ADHD (2,064 trios, 896 cases, and 2,455 controls) and EA (n=328,917) to identify ADHD-associated loci and loci overlapping between ADHD and EA. Identified single nucleotide polymorphisms (SNPs) were tested for association in an independent population-based study of ADHD symptoms (n=17,666). Genetic correlation between ADHD and EA was estimated using LD score regression and Pearson correlation.

RESULTS

At levels of condFDR<0.01 and conjFDR<0.05, we identified 5 ADHD-associated loci, 3 of these being shared between ADHD and EA. None of these loci had been identified in the primary ADHD GWAS, demonstrating the increased power provided by the condFDR/conjFDR analysis. Leading SNPs for 4 of 5 identified regions are in introns of protein coding genes (KDM4A, MEF2C, PINK1, RUNX1T1), whereas the remaining one is an intergenic SNP on chromosome 2 at 2p24. Consistent direction of effects in the independent study of ADHD symptoms was shown for 4 of 5 identified loci. A polygenic overlap between ADHD and EA was supported by significant genetic correlation (rg=-0.403, p=7.90×10-8) and >10-fold mutual enrichment of SNPs associated with both traits.

CONCLUSION

We identified 5 novel loci associated with ADHD and provided evidence for a shared genetic basis between ADHD and EA. These findings could aid understanding of the genetic risk architecture of ADHD and its relation to EA.

Maternal eating disorders and perinatal outcomes: A three-generation study in the Norwegian Mother and Child Cohort Study

Previous studies of the relationship between maternal eating disorders and adverse perinatal outcomes have failed to control for familial transmission of perinatal phenotypes, which may confound the reported association. In a unique design afforded by the Norwegian Mother and Child Cohort Study and Medical Birth Registry of Norway, we linked three generations through birth register records and maternal-reported survey data to investigate whether maternal eating disorders increase risk after parsing out the contribution of familial transmission of perinatal phenotypes. The samples were 70,881 pregnancies in grandmother-mother-child triads for analyses concerning eating disorder exposure during pregnancy and 52,348 for analyses concerning lifetime maternal eating disorder exposure. As hypothesized, eating disorders predicted a higher incidence of perinatal complications even after adjusting for grandmaternal perinatal phenotypes. For example, anorexia nervosa immediately prior to pregnancy was associated with smaller birth length (relative risk = 1.62; 95% CI [1.20, 2.14]), bulimia nervosa with induced labor (relative risk = 1.21; 95% CI [1.07, 1.36]), and binge-eating disorder with several delivery complications, larger birth length (relative risk = 1.25; 95% CI [1.17, 1.34]), and large-for-gestational-age (relative risk = 1.04; 95% CI [1.01, 1.06]). Maternal pregravid body mass index and gestational weight mediated most associations. Our results support that exposure to eating disorders increases the risk for negative health outcomes in pregnant women and their babies. (PsycINFO Database Record

Diagnostic and genetic overlap of three common mental disorders in structured interviews and health registries

OBJECTIVE

To investigate whether diagnostic data from structured interviews, primary care and specialist care registries on major depressive disorder (MDD), anxiety disorders (AD) and alcohol use disorder (AUD) identify the same individuals, yield comparable comorbidity estimates and reflect the same genetic influences.

METHODS

Registry data from primary and specialist care were available for 11 727 twins and diagnostic interview data for 2271 of these. We used logistic regression analyses and biometric modelling to investigate the overlap between the data sources.

RESULTS

Most individuals meeting diagnostic criteria at interview were not registered with a corresponding diagnosis. The rates of registration were higher for MDD (36% in primary care and 15% in specialist care) and AD (21% and 18%) than for AUD (3% and 7%). Comorbidity estimated as odds ratios, but not as polychoric correlations, was higher in the registries than in the interviews. Genetic influences on the disorders were highly correlated across data sources (median r = 0.81), bordering unity for MDD and AD.

CONCLUSION

Prevalence and comorbidity estimates differ between registries and population-based assessment. Nevertheless, diagnoses from health registries reflect the same genetic influences as common mental disorders assessed in the general population, indicating generalizability of aetiological factors across data sources.

Prediction of alcohol use disorder using personality disorder traits: a twin study

BACKGROUND AND AIMS

The DSM-IV personality disorders (PDs) are comorbid with alcohol use disorder (AUD) and with each other. It remains unclear which PD criteria are most likely to drive onset and recurrence of AUD and which are merely confounded with those criteria. We determine which individual PD criteria predict AUD and the degree of underlying genetic and/or environmental aetiology.

DESIGN

A prospective observational twin study.

SETTING

Norway 1999-2011.

PARTICIPANTS

A total of 2528 and 2275 Norwegian adult twins in waves 1 and 2 variable-selection analyses, and 2785 in biometric analyses.

MEASUREMENTS

DSM-IV PDs and their 80 criteria were assessed using a structured personal interview, and AUD using the World Health Organization's Composite International Diagnostic Interview.

FINDINGS

In a variable-selection analysis, two PD criteria were associated with AUD even after taking all the other criteria into account: criterion 8 of antisocial PD (childhood conduct disorder) and criterion 4 of borderline PD (self-damaging impulsive behaviours). Adjusting for each other, their respective odds ratios were 3.4 [confidence interval (CI) = 2.1-5.4] and 5.0 (CI = 3.3-7.7). Endorsement strength of the criteria was associated with AUD in a dose-response manner and they explained 5.5% of variation in AUD risk-more than the full diagnoses of antisocial and borderline PDs together (0.5%). The association between borderline criterion 4 and AUD 10 years later derived mainly from their overlapping genetic factors, whereas the association between antisocial criterion 8 and AUD 10 years later was due to both genetic and non-genetic factors.

CONCLUSIONS

Conduct disorder and self-harming impulsivity are the foremost risk traits for alcohol use disorder among the 80 personality disorder criteria of DSM-IV, predicting alcohol use disorder more effectively than personality disorder diagnoses. The twin-study analysis suggested that conduct disorder represents a joint genetic and developmental risk for alcohol use disorder and that impulsivity is a genetic risk.

Maternal Iodine Intake and Offspring Attention-Deficit/Hyperactivity Disorder: Results from a Large Prospective Cohort Study

Current knowledge about the relationship between mild to moderately inadequate maternal iodine intake and/or supplemental iodine on child neurodevelopment is sparse. Using information from 77,164 mother-child pairs in the Norwegian Mother and Child Cohort Study, this study explored associations between maternal iodine intake and child attention-deficit/hyperactivity disorder (ADHD) diagnosis, registered in the Norwegian Patient Registry and maternally-reported child ADHD symptoms at eight years of age. Pregnant women reported food and supplement intakes by questionnaire in gestational week 22. In total, 1725 children (2.2%) were diagnosed with ADHD. In non-users of supplemental iodine (53,360 mothers), we found no association between iodine intake from food and risk of child ADHD diagnosis (p = 0.89), while low iodine from food (<200 µg/day) was associated with higher child ADHD symptom scores (adjusted difference in score up to 0.08 standard deviation (SD), p < 0.001, n = 19,086). In the total sample, we found no evidence of beneficial effects of maternal use of iodine-containing supplements (n = 23,804) on child ADHD diagnosis or symptom score. Initiation of iodine supplement use in gestational weeks 0-12 was associated with an increased risk of child ADHD (both measures). In conclusion, insufficient maternal iodine intake was associated with increased child ADHD symptom scores at eight years of age, but not with ADHD diagnosis. No reduction of risk was associated with maternal iodine supplement use.

Maternal Symptoms of Anxiety and Depression and Child Nocturnal Awakenings at 6 and 18 Months

Objective

We aim to estimate the pathways between maternal symptoms of anxiety and depression and child nocturnal awakenings via structural equation modeling using a sibling design.

Methods

Structural equation modeling on data from 14,926 sibling dyads or triads from the Norwegian Mother and Child Cohort Study.

Results

At 6 months, we estimated the association between maternal symptoms of anxiety and child nocturnal awakenings to be owing to several nonsignificant pathways. Child nocturnal awakenings at 18 months, however, were influenced by concurrent maternal symptoms of anxiety (β = .10) and depression (β = .12). Neither maternal symptoms of anxiety (β = .04) nor depression (β = -.00) was influenced by concurrent child nocturnal awakenings.

Conclusions

Our findings suggest that maternal mental health influences child sleep behavior at 18 months after birth, and not vice versa. This is in support of hypotheses on maternal mental health influencing child sleep during toddlerhood.

Prenatal Exposure to Acetaminophen and Risk of ADHD

OBJECTIVES

To estimate the association between maternal use of acetaminophen during pregnancy and of paternal use before pregnancy with attention-deficit/hyperactivity disorder (ADHD) in offspring while adjusting for familial risk for ADHD and indications of acetaminophen use.

METHODS

Diagnoses were obtained from the Norwegian Patient Registry for 112 973 offspring from the Norwegian Mother and Child Cohort Study, including 2246 with ADHD. We estimated hazard ratios (HRs) for an ADHD diagnosis by using Cox proportional hazard models.

RESULTS

After adjusting for maternal use of acetaminophen before pregnancy, familial risk for ADHD, and indications of acetaminophen use, we observed a modest association between any prenatal maternal use of acetaminophen in 1 (HR = 1.07; 95% confidence interval [CI] 0.96-1.19), 2 (HR = 1.22; 95% CI 1.07-1.38), and 3 trimesters (HR = 1.27; 95% CI 0.99-1.63). The HR for more than 29 days of maternal acetaminophen use was 2.20 (95% CI 1.50-3.24). Use for <8 days was negatively associated with ADHD (HR = 0.90; 95% CI 0.81-1.00). Acetaminophen use for fever and infections for 22 to 28 days was associated with ADHD (HR = 6.15; 95% CI 1.71-22.05). Paternal and maternal use of acetaminophen were similarly associated with ADHD.

CONCLUSIONS

Short-term maternal use of acetaminophen during pregnancy was negatively associated with ADHD in offspring. Long-term maternal use of acetaminophen during pregnancy was substantially associated with ADHD even after adjusting for indications of use, familial risk of ADHD, and other potential confounders.

Hypnotics use in children 0-18 months: moderate agreement between mother-reported survey data and prescription registry data

BACKGROUND

Different methods in pharmacoepidemiology can be used to study hypnotic use in children. But neither questionnaire-based data nor prescription records can be considered a "gold standard". This study aimed to investigate the agreement between mother-reported questionnaire-based data and prescription record data for hypnotic drugs in children aged 0-18 months. The agreement was compared to the agreement for a group of antiepileptic drugs.

METHODS

Prescription record data were collected from the Norwegian prescription database for 47,413 children also surveyed in the Norwegian mother and child cohort between 2005 and 2009. Agreement between in the two data sources was calculated using Cohens Kappa. Multinomial logistic regression was used to calculate the effect of sociodemographic variables on discrepancies in data sources.

RESULTS

The agreement between mother-reported and dispensed hypnotics was less than 50% for all hypnotics. Sensitivity of reporting increased with number of filled prescriptions. The agreement of antiepileptic drugs was 92.9% in the same population. Of several sociodemographic factors only paternal educational level and maternal work situation was significantly related to agreement between prescription record and survey data.

CONCLUSION

There was a moderate agreement between reported use and dispensed hypnotic drugs for infants and toddlers. Results indicate that sociodemographic factors play only a minor role in explaining discrepancy.

Do DSM-5 Section II personality disorders and Section III personality trait domains reflect the same genetic and environmental risk factors?

BACKGROUND

DSM-5 includes two conceptualizations of personality disorders (PDs). The classification in Section II is identical to the one found in DSM-IV, and includes 10 categorical PDs. The Alternative Model (Section III) includes criteria for dimensional measures of maladaptive personality traits organized into five domains. The degree to which the two conceptualizations reflect the same etiological factors is not known.

METHODS

We use data from a large population-based sample of adult twins from the Norwegian Institute of Public Health Twin Panel on interview-based DSM-IV PDs and a short self-report inventory that indexes the five domains of the DSM-5 Alternative Model plus a domain explicitly targeting compulsivity. Schizotypal, Paranoid, Antisocial, Borderline, Avoidant, and Obsessive-compulsive PDs were assessed at the same time as the maladaptive personality traits and 10 years previously. Schizoid, Histrionic, Narcissistic, and Dependent PDs were only assessed at the first interview. Biometric models were used to estimate overlap in genetic and environmental risk factors.

RESULTS

When measured concurrently, there was 100% genetic overlap between the maladaptive trait domains and Paranoid, Schizotypal, Antisocial, Borderline, and Avoidant PDs. For OCPD, 43% of the genetic variance was shared with the domains. Genetic correlations between the individual domains and PDs ranged from +0.21 to +0.91.

CONCLUSION

The pathological personality trait domains, which are part of the Alternative Model for classification of PDs in DSM-5 Section III, appears to tap, at an aggregate level, the same genetic risk factors as the DSM-5 Section II classification for most of the PDs.